Al-Qassam was born in 1882 on the coastal city of Jableh in northern Syria and was educated in Al-Azar University in Cairo. After the Italian invasion of Libya in 1911, he collected funds and enlisted volunteers for Omar Mukhtar and the Libyan resistance. He later enlisted in the Ottoman army during World War I, receiving military training, and acted as a Muslim chaplain in an Ottoman army base near Damascus. With the implementation of the Sykes-Picot Agreement, al-Qassam conducted guerrilla warfare against French forces.